Aspects of the present invention relate to an apparatus to cool a computing device.
As computer and electronic systems increase in function and are found in smaller and smaller packaging, an amount of space for things like thermal management is significantly reduced. Indeed, in air cooled systems, the space allowed for packaging empty air distribution plenums is frequently the first area that is removed or severely reduced in size in order to allow for either a smaller overall package, increased amounts of electronics or both. This reduction in the space for plenums can create non-uniform airflows especially near the entrance and exhaust of the air moving devices even when all of the air moving devices are working properly. The non-uniformities in the airflow patterns can have the effect of limiting the function of the system by not providing enough cooling air to critical electrical components.
There are generally five basic solutions that have been used to address these concerns. The first is to limit the function of the system based on the cooling that is provided by the design, by either reducing the amount of electronics or reducing the function of the hot electronics. The second is to increase the size of the package to allow for larger plenums. The third is to allow for higher temperatures on the critical components and accept the increased number of thermal related failures. The fourth is to use airflow impedances that more evenly distribute the airflow but significantly reduce the overall amount of airflow in the system. The fifth is to increase the amount of air in the system by making changes to the air moving devices (e.g., using higher speed fans, larger fans, etc.). Each of these options has obvious drawbacks in the overall operability of the system.
As an additional matter, when there is a failure in one or more of the air moving devices, the problems of non-uniform airflows may be exacerbated. For example, during a failure, the forced airflow condition can turn into a natural convection condition (i.e., airflow only due to the components getting so hot that the air near the components heats up and rises away allowing cooler air to replace it) very quickly. The only acceptable solution in such cases is often to turn off the function of those electronics which are affected and typically that means turning off the entire system.